The present invention relates to an embedded magnet type rotating electric machine.
A rotor of the embedded magnet type rotating electric machine has a rotor core and a plurality of magnets embedded in the rotor core. The rotor core has a plurality of accommodating holes lined up in a circumferential direction. Each of the accommodating holes passes through the rotor core in an axial direction, and extends in a radial direction. The magnet is arranged in each of the accommodating holes.
Japanese Laid-Open Patent Publication No. 2004-173491 discloses a circumferential extension portion extending further outward in the circumferential direction with respect to an end in the circumferential direction of a magnet from a radially outer end (an outer end in a radial direction) of an accommodating hole. The circumferential extension portion increases a magnetic resistance, thereby reducing a leakage flux directly directed to an S pole of the magnet from an N pole of the magnet.
However, the publication discloses a structure in which the entire surface of a radially outer end and the entire surface of a radially inner end in each of the magnets are brought into contact with a rotor core. Accordingly, a magnetic resistance in the rotor core is still low. As a result, an effective magnetic flux of the rotor with respect to the stator is small, and a motor efficiency is low.